1. Field of the Invention
The present invention generally relates to determining the location of a communication device in a communication network. More particularly, the invention relates to determining location of a wireless communication device in a wireless communication network. Still more particularly, the invention relates to a wireless communication device determining its own location in a wireless network and requesting location-based services from the network.
2. Background Information
Wireless communication networks have become increasingly popular. In such networks, electronic devices such as notebook computers, hand held computers and the like can access a network via a wireless communication link. This permits, for example, an employee of a corporation that has a wireless network to carry his notebook computer from his office to a conference room for a meeting and still have full access to email, network files, and the like. Numerous other uses for a wireless communication network besides a corporate work environment are possible and this disclosure encompasses all such uses.
As noted in “Privacy vs Location Awareness” by Sami Levijoki, incorporated herein by reference, it is desirable to be able to determine the current location of a portable wireless device. The device's location then can be used to provide services to the device that is relevant to the device's location. An example given in the Levijoki article is that if the user of a wireless device is in Helsinki, Finland and the user is hungry, Helsinki restaurant information is more useful than information about restaurants in Paris. Besides providing information to the wireless device most pertinent to its location, device location can also be used as a security feature. That is, an employee's notebook computer located inside the employer's building might be granted a full set of access privileges, while the same device located outside the building might be granted a reduced set of access privileges.
To provide information based on device location, it is first necessary to determine the location of the device. A number of techniques for determining the location of wireless mobile devices have been suggested. In some techniques, the communication system determines or estimates the location of a portable device. In other techniques, the portable device itself is involved in determining its own location. Known implementations of both techniques have disadvantages. For those techniques in which the network determines the location of a wireless device, privacy may be an issue. That is, location of the user and the user's wireless device may be information that would be desirable to maintain confidential. The confidentiality of the user's location may be breached if the network is able to determine the device's location.
Those techniques that have been proposed for permitting the wireless device to assist in the determination as to its location are generally fairly complex. For example, the “signal strength” technique described in the Levijoki article requires signals from three different base stations to be received by a cellular telephone. The cell phone determines its location from an analysis of the three signals based on the assumption that signal strength is inversely proportional to distance. This implementation is complex and not particular exact because of environmental influences such as the user himself or herself. Further, an ultrasound-based method can be used but requires a number of ultrasound transmitters to be located at various locations in the ceiling of a building. Each wireless device includes a microphone and calculates its position based on the travel time of an ultrasonic signal between the transmitters and the wireless device. This implementation is also relatively complex.
What would be desirable is to have a wireless communication system in which the wireless devices themselves can determine their own location and do so in a relatively simple, straightforward manner.